The VA New Jersey Health Care System (VANJHCS) is requesting the funds to purchase a replacement startle/muscle tremor system for rodents. After eighteen years, the previous custom-made system has fallen upon disrepair and key replacement parts are no longer supplied. The SR-Lab System developed and produced by San Diego Instruments is considered the goal-standard for measuring the rodent acoustic startle response and pre-pulse inhibition of the startle reflex. These are assessment techniques historically used by the researchers at the East Orange VA Medical Center (EOVAMC) to study the effects of stress on startle reactivity (as a model of post-traumatic stress disorder, PTSD). In addition, recent evidence from EOVAMC researchers suggest that the startle response is dampened for long periods of time following traumatic brain injury (TBI). Two major users and two minor users at the EOVAMC require the SR-Lab System to further their work in the areas of PTSD and TBI. Two additional major users require the SR-Lab System for behavioral assessments of muscle tremors for their rodent models of Parkinson's Disease (PD). In all, this system would provide the identified users at VANJHCS with refined measures and additional measures needed to properly execute their funded projects in the absence of the previous system.